In electrical scales, round or square buttons or keys or the like are generally provided to allow the operator to control the different modes of operation of the scale. In order to effect the required switching on such a scale, the operator must visually determine the location of the appropriate button or key.
A scale is also known in which the operator-controlled key projects from the housing of the scale. The key is connected to a switching element within the housing which in turn operates the main control switch. This system is described in DE-OS No. 23 39 219. The projecting key is held in its neutral position by spring tension and must be constructed in a very stable fashion since the exact movement of the key required for switching must result even when the key is operated eccentrically.